| 1. |
- Pirdavani, Ali, et al.
(författare)
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Investigating different road safety implications of two TDM policy measures : Fuel-cost increase and teleworking
- 2013
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Ingår i: Proceedings of the 16th International Conference Road Safety on Four Continents. - Linköping : Statens väg- och transportforskningsinstitut.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Travel demand management (TDM) consists of a variety of policy measures that affect the transportation system’s effectiveness by changing travel behavior. Although the primary objective to implement such TDM strategies is not to improve traffic safety, their impact on traffic safety should not be neglected. The main purpose of this study is to investigate differences in the traffic safety consequences of two TDM scenarios; a fuel-cost increase scenario (i.e. increasing the fuel price by 20%) and a teleworking scenario (i.e. 5% of the working population engages in teleworking). Since TDM strategies are usually conducted at a geographically aggregated level, crash prediction models (CPMs) that are used to evaluate such strategies should also be developed at an aggregate level. Moreover, given that crash occurrences are often spatially heterogeneous and are affected by many spatial variables, the existence of spatial correlation in the data is also examined. The results indicate the necessity of accounting for the spatial correlation when developing crash prediction models. Therefore, zonal crash prediction models (ZCPMs) within the geographically weighted generalized linear modeling (GWGLM) framework are developed to incorporate the spatial variations in association between the number of crashes (NOCs) (including fatal, severe and slight injury crashes recorded between 2004 and 2007) and a set of explanatory variables. Different exposure, network and socio-demographic variables of 2200 traffic analysis zones (TAZs) in Flanders, Belgium, are considered as predictors of crashes. An activity-based transportation model is adopted to produce exposure metrics. This enables to conduct a more detailed and reliable assessment while TDM strategies are inherently modeled in the activity-based models. In this study, several ZCPMs with different severity levels and crash types are developed to predict the NOCs. The results show considerable traffic safety benefits of conducting both TDM scenarios at an average level. However, there are certain differences when considering changes in NOCs by different crash types.
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| 2. |
- Pirdavani, Ali, et al.
(författare)
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Traffic safety perception and its potential impact on travel demand choices
- 2016
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Konferensbidrag (refereegranskat)abstract
- In this paper we aim at investigating the potential influences of traffic safety concern and knowledge on travel demand choices and in particular travel mode choice. To this end, a survey is developed and a questionnaire is distributed to collect required information. The survey consists of several sections. First sociodemographic and socioeconomic characteristics of individuals are collected. Respondents are then asked to state their current mode choice decisions given the combination of activity type and trip length. In the next section respondents are informed of some safety figures demonstrating the general safety conditions attributed to each mode of transport. This is done with the intention of making them aware of how safe or unsafe a specific mode could be based on some empirical data. Furthermore they are asked to reveal their preferred mode they would choose by taking into account the knowledge they acquired and also from a pure hypothetical point of view without considering any additional condition. The results show that the general population does not tend to change their mode choice significantly. Moreover, their traffic safety perception was collected by asking them what they think about the probability of getting into an injury crash when taking each mode as well as the severity level of potential possible crash. The results confirmed that there is a collective conformity that public transportation is the safest mode while motorcycle followed by biking are the most dangerous modes of transport. Further analysis at the individual level is currently in progress so as to provide better mode choice models that include traffic safety along with other mode choice determinants.
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| 3. |
- Awan, Hammad Hussain, et al.
(författare)
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Analysis of merging freeways with decreasing number of lanes : a driving simulator study
- 2018
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Konferensbidrag (refereegranskat)abstract
- The main function of freeways is to provide free flow of traffic at high speeds. Merging of two freeways should therefore be designed in a way that its impact on the free flow of traffic is minimized. There are two possible ways in which merging sections of freeway are designed. First, merging of freeways with same number of lanes (i.e. number of lanes in the merged freeway equals sum of the number of lanes of two merging freeways) and, second merging of freeways with decreasing number of lanes (i.e. number of lanes in the merged freeway is less than the total number of lanes of the merging freeways). In this study, merging with decreasing number of lanes is under consideration.To design the merging section of freeways, usually the entire section is divided into three major subsections; ramp, acceleration lane and weaving section. In the Dutch Standards named “Richtlijn Ontwerp Autosnelwegen” along with the design specifications for individual elements of merging section, complete simplified designs are provided for merging sections with decreasing number of lanes for specific vehicle/capacity ratios and design speeds. In this study, we are investigating these designs in relation to the drivers’ behaviour.Objectives of this research include: 1) studying drivers’ behaviour while driving through merging designs given in the Dutch Standards and 2) comparing the efficiency of the considered designs under various heavy traffic proportions.
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| 4. |
- Bastos, Jorge Tiago, et al.
(författare)
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Road safety performance in Brazil : towards a composite indicator
- 2016
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Konferensbidrag (refereegranskat)abstract
- The monitoring of the road safety level in Brazil and particularly in its member states traditionally focuses on the available traffic fatality rates. However, this approach does not offer practical suggestions on how to improve road safety. In this context, the usage of Road Safety Performance Indicators (SPIs) is a growing and promising tendency. This research deals with the construction of a set of SPIs intended to serve as good indicators of the operational conditions of the road traffic system in each of the 27 Brazilian states. The set of 28 selected SPIs represents three domains (road user, environment and vehicle) and consists of further subdivisions. The hierarchical structure of the 28 indicators manifests the traditional distinction between the road user (RU), the environment (E) and the vehicle (V) domain of SPIs. In the first domain (1st to 10th indicator), road user behavior decomposes into alcohol (A), cell-phone (CP), protective systems (PS) and speeding (S). Protective systems decompose into seatbelt (SB) and helmet (H). In the second domain, environmental SPIs decompose into road (R) and health system (HS). Road (11th to 20ht indicator), decomposes into central division (CD), signing (SG) and roadside (RS). Signing decomposes into road markings (RM) and vertical signs (VS). Road markings decompose into central (C) and lateral (L). Health system (21st to 23rd indicator) decomposes into health professionals (HP) and health expenditure (HE). In the third domain, vehicle related SPIs (24th to 27th indicator), decompose into fleet composition (FC) and age of the fleet (AF). This paper aims to describe this innovative SPI research in Brazil, using data envelopment analysis to aggregate the SPIs into a composite indicator, as well as to show the potential for supporting future improvements on the theme.
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| 5. |
- De Ceunynck, Tim, et al.
(författare)
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Sharing is (s)caring? Interactions between buses and bicyclists on bus lanes shared with bicyclists
- 2017
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Ingår i: Transportation Research Part F: Traffic Psychology and Behaviour. - : Elsevier BV. - 1369-8478. ; 46, s. 301-315
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the results of an observation study of interactions between bicyclists and buses on shared bus lanes. The aim of the paper is to analyse bicyclists' safety on bus lanes shared with bicyclists. Straight sections of two bus lanes shared with bicyclists in Belgium are observed. All interactions between bicyclists and buses over two full weeks are recorded and analysed. Additionally, the lateral position and riding speed of bicyclists that are in interaction with buses are compared with the behaviour of bicyclists that are not in interaction with buses. One of the observed bus lanes is in line with road design guidelines in a number of countries that state that a sufficiently narrow bus lane (<3.5. m) is hypothesised to be safer than a somewhat wider bus lane; the other observed bus lane is deemed too wide according to these guidelines and is hypothesised to lead to close overtaking manoeuvres.The results show that close interactions between bicyclists and buses are relatively frequent on both types of analysed bus lanes. Close overtaking manoeuvres (a bus overtakes a bicyclist with a lateral distance less than 1. m) as well as close bicycle-following situations (a bus drives behind a bicyclist with a time gap less than 2. s) are quite common on both analysed bus lanes. The analyses could not confirm the hypothesis that a sufficiently narrow bus lane is safer than a wider bus lane. On the contrary, close interactions seem even slightly more common on the narrower bus lane. Slightly more close overtaking manoeuvres take place on the narrower bus lane, but the difference is not statistically significant. Additionally, more bicycle-following situations take place on the narrower bus lane because overtaking is more difficult. The results show that buses often maintain a close time gap in these situations. The overtaking speed of the buses is, however, significantly higher on the wider bus lane compared to the narrower one.Moreover, the presence of a bus has an influence on the behaviour of bicyclists. Bicyclists who get overtaken by a bus ride more closely to the edge of the road than bicyclists who are not in interaction with a bus. While the road design guidelines assume that bicyclists take up a width of one meter from the edge on bus lanes shared with bicyclists, the observations show that bicyclists take up much less space while being overtaken. The presence of a bus does not have a significant influence on the standard deviation of the lateral position of the bicyclist. On the narrower bus lane, some findings suggest that bicyclists who are involved in an interaction with a bus ride faster than bicyclists who are not involved in an interaction with a bus.
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| 6. |
- Hussain, Qinaat, et al.
(författare)
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The impact of perceptual countermeasures on driving behaviour in rural-urban transition : a driving simulator study
- 2018
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Konferensbidrag (refereegranskat)abstract
- Many journeys include transitions from a road stretch where the speed limit drops from higher values to lower values. These transition road segments (i.e. rural to urban) are more complex for drivers because of changes in the road environment combined with sudden speed changes (i.e. 70 kph to 50 kph in Flanders) which often yield to an inadequate adaption to the speed limits. As speed influences both the probability of a crash and its severity, these transitions could be considered as higher accidents prone zones. Furthermore, logistic models describing the relationship between impact speed and pedestrian fatality risk show that the risk increases very rapidly for any small increase in the impact speed after 50 kph. Therefore, appropriate speed management at rural to urban transitions between 70 kph and 50 kph is essential.Different types of approaches have been used to manage driving speed on roads. Allpress & Leland argued that perceptual countermeasures shape the roadside environment designs to increase drivers’ estimation or feeling of speed. This increased perceptual speed might result in an actual speed decrease. Furthermore, as previously tested by researchers, perceptual countermeasures were one of the acceptable possible solutions to adequately reduce driving speed and increase road safety at transitions. In this study, we focus more specifically on optical pavement markings of which various types exist. Optical speed bars (OSB) with reduced spacing in travelling direction were used to increase drivers’ perceptual speed; while dragon teeth markings, peripheral transverse bars and herringbone pattern were used for producing road narrowing effect. To achieve combined perceptual effects of increasing drivers’ attention, increasing perceptual speed and creating road narrowing effect, researchers tested combinations of different treatments.In the current study, we aim to achieve combined perceptual effects (i.e. increase drivers’ attention, perceptual speed and perceptual road narrowing effect) by implementing a single treatment using a driving simulator. To achieve combined perceptual effects, we introduced Optical Circles ‘OC’ with increasing diameters based on the concept of forced perspective illusion and compared with a modified form of the commonly used speed bars (i.e. Optical Bars ‘OB’ with increasing widths and decreasing spacing). To the best of our knowledge, circle markings have never used for this purpose while speed bars are commonly used with fixed width and decreasing spacing.
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| 7. |
- Shen, Yongjun, et al.
(författare)
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International benchmarking of road safety : State of the art
- 2013
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Ingår i: Proceedings of the 16th International Conference Road Safety on Four Continents. - Linköping : Statens väg- och transportforskningsinstitut.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The road traffic crashes and consequent injuries and fatalities, traditionally regarded as random, unavoidable ‘accidents’, have been more and more recognized as a preventable public health problem. Given the fact that more and more countries are taking steps to improve their road safety situation, there is a growing need for these countries to work together more closely, because there are quite a number of common problems that can be identified in close cooperation, and improvement can be expected by learning lessons from existing best practices in other countries. As a consequence, comparison between a range of countries in terms of their road safety performance and development or − using state-of-the-art terminology − inter-national benchmarking of road safety, is currently widely advocated by most countries and international bodies. However, performing a successful road safety benchmarking practice is by no means easy. Challenges exist from the definition of benchmarking framework at the very beginning to the final decisions in terms of identification of best practices and establishment of a continuous process of mutual learning. In this paper, based on a brief review of the concept of benchmarking, a benchmarking cycle for road safety is proposed. Moreover, as a valuable benchmarking tool, the development of a road safety index is highlighted, a number of recent studies are presented, and some theoretical and practical issues are discussed.
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| 8. |
- Varhelyi, Andras, et al.
(författare)
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Surrogate safety measures and traffic conflict observations.
- 2018. - first
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Ingår i: How to analyse accident causation? : A handbook with focus on vulnerable road users - A handbook with focus on vulnerable road users. - 9789089130648 ; , s. 95-128
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Bokkapitel (refereegranskat)abstract
- The chapter primarily focuses on observing traffic conflicts (also known as near-accidents) as a site-based road safety analysis technique. Traffic conflicts are a type of surrogate safety measure. The term surrogate indicates that non-accident-based indicators are used to assess VRU safety instead ofthe more traditional approach focusing on accidents (see chapter 2). The theory underpinning surrogate safety measures is briefly described, followed by a discussion on the characteristics of the traffic conflict technique. Next, guidelines for conducting traffic conflict observations using trained human observers or video cameras are presented. Chapter 4 concludes with examples of the use of the traffic conflict technique in road safety studies focusing on VRUs.
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